Generally, a fountain pen, with a head structure, has been used to write or sign documents. The head structure of fountain pen primarily includes a hood, a feed and a nib. The front end of the feed is provided with the triangular-shaped sharp member, and the back end of the feed is provided with a joint section. The shaft surface of the feed is allocated with several annularly aerating fins. The upper/bottom surfaces of the shaft are respectively provided with a diversion slip and an aerating slot. The nib is attached to an upper surface of a sharp member, which is in front of the nib, and a sleeve is used to cover the feed and the nib by a sleeve. Thereafter, an ink cartridge may be inserted at the end of the fountain pen head to form a whole foundation pen.
However, in the conventional foundation pen, the diversion slip of the front nib is the major output passage of the ink, and the diversion slip of the back nib is closed to disable it from writing when the pen is pressed in the side of back nib. Therefore, it is a disadvantage that the foundation pen is only allowed to write in the side of front nib, but not in the side of back nib. Thus, if the front nib is used in a long term of time, the sharp portion of the front nib is easy to worn to cause deformation and disable it from writing.
Finally, the sharp portion, which contacts a paper, in the conventional fountain pen, is not processed to be grounded or slipped. This causes a coarse nib that will easily scratch the paper surface or block the outflow of ink in writing.